This is one of those scratch-your-head moments when a skeptic just has to ask “Could the modelersreally have overlooked that?” Given the $79 billion odd dollars in research and the billions of dollars bet on the models, it seems hard to believe. Then again, the same team didn’t ask any hard questions when one study overturned hundreds of other studies that showed it was warmer 1000 years ago, they are the people who think it’s ok to hide declines, hide data and dodge FOI’s. This is, after all, the Team who call fertilizer – “pollution“. Maybe a couple of extra Watts per square meter could have slipped by?

When a greenhouse gas absorbs infra red, its molecules emit in a random direction — so half of its emissions are emitted up, towards space. This is kind of the key to the matter.

George is an electrical engineer, and since I’m married to one I know that EE’s are used to dealing with complex feedback loops in systems. George uses the points we know — incoming solar radiation, outgoing radiation, the Stefan-Boltzman equation — and shows in a simple and logical fashion that the numbers all balance.

But once we have this un-obfuscated picture of radiation flows from George, we can see the potential for some double-counting going on in a crucial climate calculation.

Everybody who’s anybody in the climate calculations knows that if CO2 doubles, the IPCC reckons that it is supposed to be equivalent to adding 3.7 W per square meter of net extra incoming solar energy (which means “heat”) to Earth’s big budget. Of course, adding extra CO2 to the atmosphere really just reduces the amount of radiation out to space. The flow from the sun is not increased; the 3.7 W/m-2 increase in forcing is solely due to less radiation leaving the earth.

The 3.7 W/m-2 is calculated from line-by-line spectral calculations, but does it correctly include changes to both the 93 W/m^2 going straight through the transparent window to space and the 146 W/m^2 absorbed by the atmosphere and then escaping to space?

The 1.2C no-feedbacks temperature increase from CO2 doubling is calculated by applying Stefan-Boltzman to the top of the atmosphere, where it is 255K: a surface around 255K has to warm by 1.2C if it is to emit the extra 3.7 W/m-2 required to keep the earth in radiative equilibrium when the CO2 doubles. We apply this at the top of the atmosphere because we can — we know the fluxes there and all the heat flow is by radiation. But we really want to know the change in temperature at the surface — a very different, and messier, situation. Obviously the radiative flows at the surface are only changed by about half as much due to a CO2 doubling, so presumably only about half the full 3.7 W/m-2 applies to change the surface temperature.

Like Judith Curry (see her blog, Part I and Part II), we think the calculation of a 1.2C warming for CO2 doubling is opaque and uncertain, and open to challenge. On the face of it, it may well be half that, around 0.6C. (And it’s not like those who aim to alarm us, ever exaggerate or hide behind obscure and unexplained data or calculations, is it?)

The flow-on effects of this would run rampant through the scenarios and projections. Instead of causing 1.2 degrees C of direct warming (as per Hansen et al 1984), doubling CO2 would only lead to 0.6 C, and all the feedbacks apply to that. So the “average 3 or 4 degree” estimate for the mass of climate models comes back to 1.5 – 2 degrees, and the skeptical view, which points at empirical evidence for negative feedbacks (Lindzen and Spencer) would roughly halve the 0.6C which makes 0.3C, and that converges nicely with the Miskolczi estimate of around 0.24 C.